Obesity surgery tied to lower diabetes risk in pregnancy

NEW YORK (Reuters Health) - Severely obese women who undergo weight-loss surgery may have a decreased risk of developing diabetes during future pregnancies, a new study suggests.

Researchers found that among 700 women who had undergone obesity surgery, those who'd had the procedure before becoming pregnant were 77 percent less likely to develop pregnancy-related diabetes than those who'd had a pregnancy before their surgery. They also had a lower rate of cesarean section.

The findings, published in the Journal of the American College of Surgeons, add to evidence of the potential health benefits of weight-loss surgery.

Research has shown that the surgery, which restricts the amount of food a person can eat, can spur substantial weight loss and help control obesity-related conditions like type 2 diabetes.

Studies have come to conflicting conclusions, however, regarding the effects on gestational diabetes, a form of the disorder that arises during pregnancy.

While gestational diabetes usually resolves after childbirth, during pregnancy it may cause the fetus to grow abnormally large, which can make a C-section or forceps necessary and raise the risk of postpartum bleeding. Women who develop gestational diabetes are also at increased risk of type 2 diabetes later in life.

For the new study, Dr. Anne E. Burke and colleagues at Johns Hopkins University in Baltimore reviewed insurance records of 23,594 U.S. women who had undergone obesity surgery between 2002 and 2006.

Of those women, 346 had given birth during that same time period, but before having the surgery; another 354 had given birth after the surgery -- typically about 20 months later.

Most had undergone gastric bypass, in which the upper portion of the stomach is stapled off to create a small pouch that restricts the amount of food a person can eat at one time. The surgeon also creates a bypass around the rest of the stomach and a portion of the small intestine, which limits the body's absorption of food.

A minority -- 42 women overall -- had undergone gastric banding, where an adjustable band is used to create the pouch at the upper part of the stomach.

Burke's team found that among women who had delivered before weight-loss surgery, 27 percent developed gestational diabetes during the pregnancy. That compared with eight percent of those who'd delivered after their surgery.

Similarly, the rate of C-section was lower in the former group: 28 percent versus 43 percent.

The researchers then factored in two other variables: the women's age and whether they had ever had a C-section in the past, which raises the odds of having one in subsequent pregnancies. With those factors considered, obesity surgery was linked to a 77 percent reduction in the risk of gestational diabetes and a 52 percent decrease in the odds of C-section.

The findings "add to a growing body of evidence in favor of a protective effect" of weight-loss surgery against gestational diabetes and C-section, Burke told Reuters Health.

However, she added, "I do not think this is saying that obese women need to delay pregnancy until after having this surgery."

For one, only certain, severely obese women would be candidates for the procedure. Moreover, Burke pointed out, women should first try to shed weight through diet and exercise before turning to surgery.

The study has limitations, the researchers acknowledge. Chief among them is the fact that it was a review of insurance records, rather than a controlled study where women were recruited and then followed over time to compare the pregnancy outcomes of those who had obesity surgery with those who did not.

According to Burke, it would be difficult, for both practical and ethical reasons, to conduct a randomized, clinical trial -- in which women would be randomly assigned to have weight-loss surgery either before or after a pregnancy.

But, she noted, it would be more feasible to do a study where women were followed over time to look at the pregnancy outcomes of women who chose to have weight-loss surgery and those who did not.

In general, weight-loss surgery may be an option for people with a body mass index (BMI) of 40 or higher, which puts them in the category of severe obesity. It may also be an option for people who are less severely obese but have chronic medical conditions like type 2 diabetes or high blood pressure.

The risks include short-term complications from surgery, like serious bleeding, infection and blood clots; longer-term risks include vitamin and mineral deficiencies and hernia development. And an estimated 10 percent of patients have an unsatisfactory weight loss or eventually regain much of the weight they had shed.

An estimated 220,000 Americans underwent some form of weight-loss surgery, most often gastric bypass, in 2009, according to the American Society for Metabolic & Bariatric Surgery.

On average, the procedures cost about $20,000 to $25,000. Whether surgery is a cost-effective way to prevent gestational diabetes is a question for future research, according to Burke's team.

A study published last month found that weight-loss surgery may curb the costs of managing type 2 diabetes.

The study, which examined insurance claims of more than 2,200 weight-loss surgery patients, found that among those with diabetes before the surgery, only 15 percent were still taking diabetes medications two years after the procedure. (See Reuters Health story of August 16, 2010.)

Diabetic patients' yearly healthcare costs averaged nearly $6,400 in the two years before surgery; the typical cost of the surgery plus hospitalization was almost $30,000.

The researchers concluded that because the weight loss won by surgery can be maintained for years, the procedure could be cost-saving in the long run for people with type 2 diabetes.